Make class of static functions in rtp_to_ntp.h:

webrtc/modules/rtp_rtcp/include/remote_ntp_time_estimator.h

 /*
  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS.  All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
 #ifndef WEBRTC_MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_
 #define WEBRTC_MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_
 
 #include <memory>
 
 #include "webrtc/base/constructormagic.h"
-#include "webrtc/system_wrappers/include/rtp_to_ntp.h"
+#include "webrtc/system_wrappers/include/rtp_to_ntp_estimator.h"
 
 namespace webrtc {
 
 class Clock;
 class TimestampExtrapolator;
 
 // RemoteNtpTimeEstimator can be used to estimate a given RTP timestamp's NTP
 // time in local timebase.
 // Note that it needs to be trained with at least 2 RTCP SR (by calling
 // |UpdateRtcpTimestamp|) before it can be used.
 class RemoteNtpTimeEstimator {
  public:
   explicit RemoteNtpTimeEstimator(Clock* clock);
 
   ~RemoteNtpTimeEstimator();
 
   // Updates the estimator with round trip time |rtt|, NTP seconds |ntp_secs|,
   // NTP fraction |ntp_frac| and RTP timestamp |rtcp_timestamp|.
   bool UpdateRtcpTimestamp(int64_t rtt, uint32_t ntp_secs, uint32_t ntp_frac,
                            uint32_t rtp_timestamp);
 
   // Estimates the NTP timestamp in local timebase from |rtp_timestamp|.
   // Returns the NTP timestamp in ms when success. -1 if failed.
   int64_t Estimate(uint32_t rtp_timestamp);
 
  private:
   Clock* clock_;
   std::unique_ptr<TimestampExtrapolator> ts_extrapolator_;
-  RtcpMeasurements rtcp_list_;
+  RtpToNtpEstimator rtp_to_ntp_;
   int64_t last_timing_log_ms_;
   RTC_DISALLOW_COPY_AND_ASSIGN(RemoteNtpTimeEstimator);
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_RTP_RTCP_INCLUDE_REMOTE_NTP_TIME_ESTIMATOR_H_